<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>练习</title>
    <style>
        ul#awesome{
            color: red;
        }
        ul.shoppin-list li.favorite span{
            color: blue;
        }
    </style>
</head>
<body>
    <ul class="shoppin-list" id="awesome">
        <li><span>milk</span></li>
        <li class="favorite" id="must-buy">
            <span class="hight">saugage</span>
        </li>
    </ul>
    <br>
    <br>
    <table id="mytable" border="1">
        <tr>
            <td>1</td>
            <td>2</td>
            <td>3</td>
        </tr>
        <tr>
            <td>4</td>
            <td>5</td>
            <td>6</td>
        </tr>
        <tr>
            <td>7</td>
            <td>8</td>
            <td>9</td>
        </tr>
    </table>


    <script src="jquery-3.1.0.js"></script>
<script>
    /*var  mytable = document.getElementById('mytable');
    var tr = mytable.getElementsByTagName('tr');
    var td = tr[1].getElementsByTagName('td');
    td[1].innerHTML = 55;
    td[1].style.backgroundColor='red';*/

    var $i = $('td:eq(1)','tr:eq(1)');
        $i.html(55).css('background','red');

    /*$('td:eq(4)').html('55').css('background','red');*/

   /* function(date){
        var Date = new date();
             Y = date.getFullYear();
             M = date.getMonth();
             D = date.getDate();
             H = date.getHours();
             m = date.getMinutes();
             S = date.getSeconds();
        var timer = Y+":"+M+":"+D+":"+H+"+"+m+":"+S;
        console.log(timer);
    }
    date();*/
</script>
</body>
</html>